Hmmm, as a smoker who smoked cigarettes for 25 years and then stopped I feel I have to say something here. Well, actually I don't, but I'm going to anyway!
Firstly, it doesn't matter what you burn - tobacco, hemp, incense, horse dung - the smoke part is actually detrimental to your lungs (working for over a decade in pathology will demonstrate this fact rather vividly). You don't even have to be an active participant: people who die after living in cities all their lives often have noticeable carbon deposits in their lungs. Bottom line: all smoke is bad for your lungs, but your lungs can cope as long as the exposure is neither acute nor chronic.
Secondly, nicotine in its refined form is exceptionally addictive and exceptionally powerful (and, I believe, was used as a narcotic anaesthetic for a time), although the amount in tobacco products is almost vanishingly small.
Now, for those who smoke but would rather not. In my personal experience of many failed attempts to quit smoking it dawned on me one day (after 25 years of trying!) that the whole concept of 'giving up' is inherently a process- that is, it has a beginning, a middle and an end. As it is a process it is subject to potential failure. It seems that, whether we like it or not, the predominant mindset of people today is that failure is okay as long as we tried.
This has basically given a lot of people a 'get out of jail free card'. They tried, they failed, what can you do? Well, the most successful quitters are the ones that just quit! For these people (and for me) there is no longer a process. One moment they are smokers, the next they are non-smokers. Note - I say non-smokers rather than ex-smokers because the latter term still contains the hint of a 'process'.
Regarding support: people around you asking how you are doing today, whether you are having cravings or bad withdrawal symptoms... these people are not helping but challenging you. They are constantly bringing your attention back to something you have put behind you. Their intention is good, but their means are not skillful in the least. Quitters would do well to tell their nearest and dearest to not ever mention smoking. Actually, my workplace was fantastic. A couple of people queried whether I still smoked, and when I said no they said 'well done' and never raised the subject again. Perfect!
Lastly, picking a day/time to stop is generally not very helpful either. It has the tendency to create a wave of stress leading up to the event which inhibits success. For me, it just happened one day. I woke up, reached for the cigs, realised I had none, made the decision to be a non-smoker. That was 5 years ago and I have never been tempted back. In fact I find other people's smoke, even on the street, to be quite unpleasant.
Sorry, I feel strongly on the subject. While I wouldn't force anyone to do something against their desire, I would like to offer a potential way forward for those who seek change.